In the last few years a high emphasis has been placed on the design and use of PET cameras for small animal studies, for example, to aid in the development of human gene therapies by imaging transgenic animals such as mice. Although, such techniques have an extraordinary potential for both clinical and basic biomedical science applications, its full realization is severely hampered by the expense, complexity and physical limitation of crystal detectors widely used in today's cameras. In particular, crystals are costly and very difficult to segment to the desired 1 mm level. Furthermore, depth of interaction error in the 1 cm or greater crystal depth required causes severe degradation of off-axis resolution. This project seeks to develop enhanced high resolution PET through the highly novel approach of the lead walled straw (LWS). In a Phase I NIH project, feasibility of application of this high energy physics spinoff technology has been proven, and in fact it has been demonstrated that considerably enhanced imaging characteristics can be achieved. A 2 mm LWS modular unit has been developed which has produced 1.0 mm FWHM axial spatial resolution. When utilized in ring arrays, such a module will produce a reconstructed volumetric spatial resolution of less than 2 μl, which is a factor of 8 improvement compared to the best commercial camera. Furthermore axial sensitive field of view can be readily extended to as large as 20 to 40 cm, and very high sensitivity can be achieved at modest cost.